The
Antiference X17 was a combined Band I and Band III array. The
band I section was an X aerial, the patented Antex.
This was not a deformed yagi as is often supposed, but had one
active element at the rear. The other three were connected to
the coaxial braid, but were insulated from the mast or boom. The
seven element Band III section was a yagi, but the rear reflector
was in fact the two front elements of the Band I aerial. Note
that the dipole is not folded, and has its ends bent so that they
do not foul the Band I elements. The two sections are linked by
twin feeder, the downlead being connected at the Band III end.
These arrays were not commonly used for horizontal polarisation,
as shown here, because the directional properties of the Antex
were not good in that plane, and because the two sections had
to point in the same direction when used horizontally.